Implement OFDMA , MIMO for WiMAX , LTE MIMO / OFDM

The wireless industry is in transition. All of the new 4G air-interfaces—WiMAX, Long Term Evolution, Ultra Mobile Broadband, 802.20, Wireless Broadband, next-generation PHS and the like—share some things in common: all are based on OFDM Access (OFDMA); all exploit MIMO; and all have «flattened architecture» and all are Internet Protocol-based. This article discusses WiMAX and LTE: in particular, how to implement the core DSP algorithm of OFDMA, then the novel variant used by LTE for the uplink, and finally a brief discussion on MIMO for both WiMAX and LTE. It describes these in the context of a software-defined flexible architecture. OFDM uses a large number of closely spaced orthogonal subcarriers. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation) at a low symbol rate, maintaining data rates similar to conventional single-carrier modulation schemes in the same bandwidth. OFDMA is the enhancement that enables multiple users to share the channel by allocating them particular tones.